docs: def _add_handler(logger, handler=None, loglevel=None):
      """
      Add a handler to an existing logging.Logger object
      """
      handler.setLevel(loglevel or DEFAULT_LOGLEVEL)
      if handler.level <= logging.DEBUG:
          _fmt = '%(asctime)s| %(levelname)-4.3s|%(threadName)10.9s/' \
                 '%(lineno)04d@%(module)-10.9s| %(message)s'
          handler.setFormatter(logging.Formatter(_fmt))
      else:
          handler.setFormatter(logging.Formatter(
              '%(asctime)s| %(levelname)-8s| %(message)s'
          ))
      logger.addHandler(handler)